Method and apparatus for controlling a brushless DC motor

Claim 2

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a circuit detecting rotor position in response to the first comparison circuits, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying a specific conduction pattern to each stator winding when the rotor is stopped; a second comparison circuit for comparing a reference output determined for the conduction pattern with the outputs of the first comparison circuits when the conduction circuit is conducting; and an abnormality detection circuit detecting abnormalities based on the comparison results of the second comparison circuit.

Claim 3

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a circuit detecting rotor position in response to the first comparison circuits, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for selectively supplying a first conduction pattern in which all the stator windings take higher voltages than the specified reference voltage and a second conduction pattern in which all the windings take a lower voltage than the specified reference voltage while the rotor is stopped; a second comparison circuit for comparing a reference output determined for each conduction pattern and the output of the first comparison circuits when the conduction circuit is supplying the first and second conduction patterns; and an abnormality detection circuit for detecting abnormalities based on the comparison results of the second comparison circuit.

Claim 4

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a circuit detecting rotor position in response to the first comparison circuits, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for selectively supplying a first conduction pattern in which all the stator windings take higher voltages than the specified reference voltage and a second conduction pattern in which all the windings take a lower voltage than the specified reference voltage while the rotor is stopped; a second comparison circuit for comparing a reference output determined for each conduction pattern and the output of the first comparison circuits when the conduction circuit is supplying the first and second conduction patterns; and an abnormality detection circuit for detecting abnormalities based on the comparison results of the second comparison circuit.

Claim 5

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a second comparison circuit comparing comparison outputs of the first comparison circuits with a reference signal; a circuit for detecting rotor position in response to the second comparison circuit, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying multiple conduction patterns in which windings of one phase or two phases are at lower voltages than a specified reference voltage and a remaining stator winding is at a higher voltage than the specified reference voltage while the motor is stopped; a third comparison circuit for comparing a reference output determined for the conduction patterns with the output of the second comparison circuit when the conduction circuit is conducting; and an abnormality detection circuit for detecting abnormalities based on the comparison results of the third comparison circuit.

Claim 6

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a second comparison circuit comparing comparison outputs of the first comparison circuits with a reference signal; a circuit for detecting rotor position in response to the second comparison circuit, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying multiple conduction patterns in which windings of one phase or two phases are at lower voltages than a specified reference voltage and a remaining stator winding is at a higher voltage than the specified reference voltage while the motor is stopped; a third comparison circuit for comparing a reference output determined for the conduction patterns with the output of the second comparison circuit when the conduction circuit is conducting; and an abnormality detection circuit for detecting abnormalities based on the comparison results of the third comparison circuit.

Claim 7

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, which compare a specified reference voltage with the stator winding terminal voltages; a circuit which detects rotor position in response to the first comparison circuits, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit which supplies multiple conduction patterns in which windings of one phase or two phases are at lower voltages than a specified reference voltage and a remaining phase stator winding is a higher voltage than the reference voltage while the brushless motor is stopped; a second comparison circuit which compares a reference output determined for the conduction pattern and the outputs of the first comparison circuits during conduction by the conduction circuit; and an abnormality detection circuit which detects abnormalities in response to the comparison results of the second comparison circuit.

Claim 8

A control apparatus for a brushless DC motor which has a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, which compare a specified reference voltage with the stator winding terminal voltages; a circuit which detects rotor position in response to the first comparison circuits, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit which supplies multiple conduction patterns in which windings of one phase or two phases are at lower voltages than a specified reference voltage and a remaining phase stator winding is a higher voltage than the reference voltage while the brushless motor is stopped; a second comparison circuit which compares a reference output determined for the conduction pattern and the outputs of the first comparison circuits during conduction by the conduction circuit; and an abnormality detection circuit which detects abnormalities in response to the comparison results of the second comparison circuit.

Claim 9

A control apparatus according to one of claims 1 to 3, wherein the conduction circuit conducts current to each winding prior to activation of the brushless DC motor before a starting of motor operation.

Claim 10

A control apparatus according to claim 1, 2 or 3, further including an indication circuit for indicating the abnormality, when the abnormality detection circuit has detected an abnormality.

Claim 11

A control apparatus according to claim 1, 2 or 3, further including: a current detection circuit which detects the current flowing in the motor; and a conduction prohibition circuit which prohibits conduction of current to the stator windings after the current detection circuit has detected an over-current during conduction to the windings by the conduction circuit.

Claim 12

A control apparatus according to claim 7, further including an indication circuit which indicates an over-current abnormality when the current detection circuit has detected an over-current during conduction to the windings by the conduction circuit.

Claim 13

A control apparatus according to one of claim 1, 2 or 3, wherein the reference voltage is a voltage approximately intermediate between the DC voltage inputs to the brushless DC motor.

Claim 14

A control apparatus according to claim 1, 2, 3 or 4, further including a fan which is rotated by the brushless DC motor.

Claim 15

A control apparatus according to claim 1, 3 or 4 wherein the specified reference voltage is a neutral point potential of the 3-phase stator winding.

Claim 16

An air conditioner having a sealed compressor and a compressor motor, which is built into the sealed compressor, having a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a circuit for detecting rotor position in response to the first comparison circuits based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying a specific conduction pattern to each stator winding when the rotor is stopped; a second comparison circuit which compares a reference output determined for the conduction pattern with the outputs of the first comparison circuits when the conduction circuit is conducting; and an abnormality detection circuit which detects abnormalities based on the comparison results of the second comparison circuit.

Claim 17

An air conditioner having a sealed compressor and a compressor motor, which is built into the sealed compressor, having a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a circuit for detecting rotor position in response to the first comparison circuits based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying a specific conduction pattern to each stator winding when the rotor is stopped; a second comparison circuit which compares a reference output determined for the conduction pattern with the outputs of the first comparison circuits when the conduction circuit is conducting; and an abnormality detection circuit which detects abnormalities based on the comparison results of the second comparison circuit.

Claim 18

An air conditioner having a sealed compressor and a compressor motor, which is built into the sealed compressor, having a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a second comparison circuit comparing comparison outputs of the first comparison circuits with reference signal; a circuit for detecting rotor position in response to the second comparison circuit, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying multiple conduction patterns in which windings of one phase or two phases are at lower voltages than a specified reference voltage and a remaining stator winding is at a higher voltage than the specified reference voltage while the motor is stopped; a third comparison circuit for comparing a reference output determined for the conduction patterns with the output of the second comparison circuit when the conduction circuit is conducting; and an abnormality detection circuit for detecting abnormalities based on the comparison results of the third comparison circuit.

Claim 19

An air conditioner having a sealed compressor and a compressor motor, which is built into the sealed compressor, having a permanent magnet rotor and a 3-phase stator winding for applying a rotating magnetic field to the permanent magnet rotor, comprising: a plurality of first comparison circuits, one provided for each phase, for comparing a specified reference voltage with the stator winding terminal voltages; a second comparison circuit comparing comparison outputs of the first comparison circuits with reference signal; a circuit for detecting rotor position in response to the second comparison circuit, based on induced voltages generated in the stator windings which are non-conducting when the motor is rotated, the circuit switching conduction to each stator winding in response to detection of the rotor position; a conduction circuit for supplying multiple conduction patterns in which windings of one phase or two phases are at lower voltages than a specified reference voltage and a remaining stator winding is at a higher voltage than the specified reference voltage while the motor is stopped; a third comparison circuit for comparing a reference output determined for the conduction patterns with the output of the second comparison circuit when the conduction circuit is conducting; and an abnormality detection circuit for detecting abnormalities based on the comparison results of the third comparison circuit.